Stock Option Activity (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Share-based Arrangements with Employees and Nonemployees [Abstract]
Shares outstanding at beginning of period	2,020,308	2,540,677	2,105,152	2,621,686
Shares granted	10,000	77,500	34,000	157,000
Shares exercised	(117,502)	(106,781)	(191,059)	(204,090)
Shares forfeited or expired	(37,326)	(141,311)	(72,613)	(204,511)
Shares outstanding at end of period	1,875,480	2,370,085	1,875,480	2,370,085
Weighted average exercise price of options outstanding at beginning of period	$ 13.51	$ 13.24	$ 13.34	$ 13.03
Weighted average exercise price of options granted	$ 15.04	$ 16.52	$ 15.24	$ 15.90
Weighted average exercise price of options exercised	$ 3.54	$ 7.82	$ 4.89	$ 7.05
Weighted average exercise price of options forfeited or expired	$ 20.44	$ 16.00	$ 19.29	$ 16.81
Weighted average exercise price of options outstanding at end of period	$ 14.01	$ 13.42	$ 14.01	$ 13.42